基于走航监测的煤矿甲烷排放量化

Coal mine methane emissions quantification based on vehicle-based monitoring

对增温贡献最大的“非二”温室气体--甲烷(CH_(4))排放的准确核算,是制定减排政策与检验减排效果的基础。针对“自下而上”方法对煤矿CH_(4)排放量化的不足,本研究系统考虑山西省晋城市某一示范煤矿区的地形、气象条件和基础设施分布,基于搭载了高精度温室气体分析仪的走航监测平台,结合移动式与下风向静止式两种监测方法,利用AERMOD大气扩散模型反演煤矿CH_(4)排放强度,并获得重点排放源的CH_(4)排放因子。结果表明,非生产状态下,单个风井排放速率为763 kg/h,比正常工况下的企业排放数据低了15.9%;在不考虑无组织排放的情况下,整个园区的CH_(4)排放因子为15.09 m^(3)/t,比“自下而上”清单低了13.8%,说明矿区工况对CH_(4)排放起到较大影响。煤矿园区的主要排放点源为1个风井与2个抽放泵站排气口,而无组织排放源为6个原煤仓;三者的排放因子呈现出递减变化,分别为8.6 m^(3)/t(43%)、6.49 m^(3)/t(33%)和4.87 m^(3)/t(24%)。传统的“自下而上”方法由于缺少对无组织排放源的考虑,即便在非生产状态下,也会造成整个矿区甲烷排放近24%的低估,而基于走航监测的甲烷核算方法能够弥补这一缺失。

Obtaining accurate emissions of methane(CH_(4)),one of the most important non-carbon-dioxide greenhouse gases,is the basis for formulating and validating emission reduction policies.In terms of shortcomings from the"bottom-up"approach,this study combined the vehicle-based monitoring and the AERMOD atmospheric dispersion modeling system to derive the emission rates and emission factors of main CH_(4)sources in one demonstration coal mine in Jincheng city,Shanxi province.After systematically considering the topography,meteorological conditions,and infrastructure distribution of the coal mine,both the mobile and downwind stationary monitoring alternatives were adopted,using a platform equipped with a high-precision greenhouse gas analyzer.Results showed that the simulated CH_(4)emission rate of a single ventilation shaft under non-production condition(763 kg/h)was about 15.9%lower than the data provided by the enterprise in production.If ignoring the fugitive emissions,the derived CH_(4)emission factor of the coal mine was 15.09 m^(3)/t,which was 13.8%smaller than that in"bottom-up"inventory,indicating that the working conditions of the coal mine played a large role in CH_(4)emissions.One ventilation shaft and two vent stacks in the gas gathering station were the main point sources,and six coal silos were the fugitive sources,the emission factors of which were 8.6 m^(3)/t(43%),6.49 m^(3)/t(33%)and 4.87 m^(3)/t(24%),respectively.The traditional"bottom-up"accounting without consideration of fugitive emissions,resulted in a nearly 24%underestimation of CH_(4)emissions even under non-production conditions,which could be compensated by the methane quantification method based on vehicle-based monitoring.